Acid dyeing process using alkanesulfonic acids



Patented Oct. 30, 1951 UNITED STATES PATENT OFFICE ACID DYEING PROCESS USING ALKANE- SULFONIC ACIDS Anthony M. Schwartz, Washington, D. 0., as-

signor to Standard Oil Company, Chicago, Ill.,

a corporation of Indiana No Drawing. Application July 9, 1949, Serial No. 103,945

7 Claims. (Cl. 8-43) quantity of sulfuric acid needed may range from 1% to based. on the weight of the goods. In many instances the goods must be boiled in the dyebath for as long as 2 or 3 hours, and the acid causes appreciable degradation and weakening of the wool.

The chromiferous acid dyes, of which the Neolans (Ciba) and the Chromacyls (du Pont) are representative, are noted for requiring high acid concentrations and long boiling times. In spite of these disadvantages they are widely used because of their superior fastness properties. The Neolan dyes are soluble chromium co-ordination complexes of lake-forming azo dyes. They are prepared from suitable dyes, usually from o,o-di hydroxy azo dyes, by heating, e. g. boiling under reflux, with a salt of tervalent chromium.

It is an object of this invention to provide novel acid dye baths for dyeing wool or other acid-sensitive protein fibers. Another object of this invention is to provide acid dye baths for wool and the like wherein part or all of the sulfuric acid which is commonly employed in such baths is replaced by an alkansulfonic acid containing 1 to 4 carbon atoms, inclusive, in the alkyl group. A further object of this invention is to provide metallized acid dye baths for W001 and the like comprising essentially an alkanesulfonic acid poncontaining 1 to 4 carbon atoms, inclusive, in the alkyl group. Yet another object of this invention is to provide level, rapid-acting acid dye baths for W001 and the like which do not induce substantial degradation in the Wool, hair, or other protein-type fiber which is being dyed. Still another object of this invention is to provide acid dye baths for W001 containing sulfuric acidand C1C4 alkanesulfom'c acids, which baths retain the advantages of sulfuric acid dye baths but' present important advantages over sulfuric acid dye baths. vention will become apparent from the ensuing description thereof.

I have made the surprising discovery that alkanesulfonic acids containing 1 to 4 carbon atoms, inclusive, in the alkyl group, or their mixtures, are even more effective than sulfuric acid in forcing acid dyes onto wool fibers and, additionally, present the important advantage over sulfuric acid in causing substantially less degradation of wool fiber.

In the following table are presented some examples which are illustrative of the present invention. The acid dyeings of woolen fabrics were all carried out on a standard lot of 7 oz. white flannel. Two percent dye and from 1 to 8% acid (on the weight of the goods) was used. The bath ratio was 40 to 1. The weighed swatch of wool was added to the measured amount of cold water. The acid was then added and allowed to stand 5 minutes at room temperature. The bath was then warmed to F., the dye added and stirred in. The bath was then brought to the boil within a-period of one-half hour, and boiling was continued for one and one-half hours. The switch was then removed, rinsed in warm water, and air dried. The rate of dyeing, the exhaust (i. e. the amount of dyestufi left in solution at the end of the boil), and the amount of dye in the rinse water were estimated visually. Three different dyes were used, all of which contain chromium bound in the dyestulf molecule by coordinate linkages. These dyes were: Chromacyl Bordeaux R (du Pont) Chromacyl Yellow N (du Pont) and Neolan Red 33 (Ciba). Strength tests were made on a Scott inclined plane tester after the samples had been subjected to 1500 cycles on a Taber Abraser instrument. The al- These and other objects of this in-- kali solubility test, which is one of the best indexes of the amount of damage suffered by a sample of wool, was carried out according to the standard procedure as follows: A 1 gram sample of wool is dried at 110 C. and weighed accurately. It is then placed in a tube containing 100 ml. of 0.1N NaOI-I solution and held at 65 C. for 1 hour. The material is then rinsed in running tap water for 6 minutes, dried at 110 C. overnight, and weighed. The percentage weight loss is equal to the alkali solubility.

In the following tables the abbreviation ASA refers to a mixture of C1-C4 alkanesulfonic acids containing a small amount of sulfuric acid, of the order of about 1 to 2 percent. This mixture of alkanesulfonic acids was prepared by thecataly tic oxidation of a mixture of the corresponding disulfides with air, employing small proportions;

of nitrogen oxides as the catalyst, as described and claimed in U. 8. Patent 2,433,395 of W. A. Proell and B. H. Shoemaker, patented December 30, 1947.

TABLE 1 The data in Table 1 clearly show that the loss in strength suffered by wool is considerably less with the alkanesulfonic acid than with sulfuric acid. This effect is particularly important in the case of carpet yarns, upholstery fabrics, etc., where wear-resistance is paramount. It is also very important in the case of bleached wools, shrink-resistant wools and other specially finished wools which tend to lose strength in wet processing more readily than unfinished fabrics.

It was noted that 3% alkanesulfonic acid is sufficient to insure good exhaust and dye fixation, equal to that obtained with 6-8% H2804 (run 11). Even at 8% alkanesulfonic acid, however, the alkali solubility is. within allowable limitswhereas 8% H2804 causes marked degradation.

One eifect of dyeing with alkanesulfonic acids as the acid constituent of the dye bath is that a slightly difierent dye shade is produced upon the wool than is obtained with sulfuric acid dye baths. It was believed possible that oxidative damage to the surface of the W001 might be con- Dyeing with Neolan colors. Arms 7 oz. woolflannel, secured and carbonized St in t Per reng 1 o u- Run Cent Type Dye lbs'z/in. Pbiliyt m r t er en None 8. 7 Chrgmacyl Bordeaux R 13. 2 17.7 18. 3 16. 9 2112 18.9 19.4 18. 7 17.3 20. 8 9. 9 19.7 9. 8 10. 4 20. 3 113 .do 14.5. Chromacyl Yellow N 20.3 9. 4 Neolan Red 313 21.5 8. 5

1 After 1500 cycles on Taber.Abraser instrument. 1 Measured without previous abrading treatment.

It was determined that-much less alkanesulfo'nic acid than H2804 is needed to give a satisfactory depth "of shade and dye-exhaust. 'About 4' to 8% H280; is required. to accomplish the same results as 1 to 3% alkanesulfonic acid. The effect on fabric strength: andv alkali solubility of-various dyeing treatments involving alkanesulfoni'c-acid and-1152804 is shown inaTable 1. The 'controls show an: alkali solubility of' about 9.% :and a breaking strength-of aboutz20.5pounds. Eighty-percent H28O4 seriously degrades the fabric;;bringing the :breaking strength down to about 17- 'poundsqand the alkali solubility up to over 214% (runfi). Inone experiment, 8% alkanesulfonicacid gave a-much more complete exhaust, caused-no appreciable loss in breaking strength and increased the alkali solubility by only about 2- points, from 9% to 11% (run 12). Ithad roughly the same damaging effect as l.5% H2804, which isfar below theamount of H280; needed for satisfactory dyeing.-

One .percent alkanesulfonic acid gives a satisfactory dying about. equivalent to that obtained with 6% H2804 (run 9). The-results show that in every case the alkanesulfonic acid causes no substantial degradation whereas H2804, when employed in amountsnecessary for gooddyeing, doubles the. alkali solubility. and causes a definite decrease in the breaking strength of wool fiber.

nected with the shade difierences between alkanesulfonic acids. andsu-lfuric acid, on the theory thatsulfuric acidoxidizes wool sufficiently to ,develop. areddish shade, whereas ..the non-oxidiz-v ing alkanesulfonic acids do'not have this. effect.

Samples of the test flannel were accordingly bleached-by a standard procedurequsing H202, and were then dyed; in the presence-of mixed C1-C4 alkanesulfonic-acids.- The results: are shown in Table 2. The bleached samplesdyed a-somewhat bluer shade in alkanesulfonic'acid baths than with H2804, but the blueing efiect was much less than in the case of unbleached wool. It was slightly greater, however, than the very'weak blueing efiect encountered with Harriset-treated wool. It is noteworthy that the initial alkali solubility ofthe bleached wool is high, as expected, but very little further damage occurs in dyeing with alkanesulfonic acid baths.

The results in Table 2 also show that 3% alkanesulfonic acid and 2% H2804 used in conjunction give practically the same shade as 8% H2804. In many instances it is probable that even 1% H2804 with 2 or 3% alkanesulfonic acid would give a satisfactory shade. The degree of damage afforded b this combination is still much lower than that obtained with a percentage of straight H28O4'adequate for dyeing:

TABLE 2 Shade change of Ames 7 oz. grey wool flannel dyed with Chromacyl Bordeaux R Pre-Treatment Acid (Per Cent) Alkali Solubility (Per Cent) Shade 3% ASA-+40% NMSO MW 1% ASA Standard bordeaux.

Bluer, same strength. Bluer, slightly stronger. Sl. bluer, sl. stronger. V. sl. bluer, sl. stronger.

Do. Almost same shade. strength. V. much bluer, sl. weaker.

Do. V. much bluer and much weaker. Much bluer. same strength. Sl. bluer, stronger.

1 Active chlorine treatment to nroduce a shrink-resistant fabric.

1 This sample not dyed before measuring ulkali solubility.

In Table 3 are presented data concerning the color fastness to water obtained with acid dyeing baths containing varying amounts of alkanesulfonic acids (C1-C4) and sulfuric acid. The dyed fabric (2 g.) was boiled in 40 g. of water and the relative amount of the dye leached out by the water was estimated; 1 denotes the least amount that was leached. It will be noted from Table 3 that with 3% of alkanesulfonic acid, the fastness is equal to that obtained with sulfuric acid. With sulfuric acid, in any quantity down to 1.5%, the dyeings are all of about the same water fastness. sulfonic acids the rate of dyeing is extremely rapid, the dye bath is completely exhausted in one-half hour or less and the alkali solubility of the wool is increased by only a small amount; With 8% of the alkanesulfonic acids the fastness of the dye to water is superior to that obtained with sulfuric acid.

TABLE 3 Color fastness of 7 oz. Ames grey wool flannel dyed with Cfhromac'yl Bordeaux R Relative Amount of Color in Water Per Cent Acid Used in Dyeing With 8% f the alkane TABLE 4 Relative lightfastness of wool flannel dyed with Chromacyl Bordeaux R, after 77 hours in the Weather-O-Meter The data in Table 5 indicate that acetic acid cannot be substituted for C1-C4 alkanesulfonic acids in mixtures with sulfuric acid in dye baths. The data clearly indicate that acetic acid, when substituted for the alkanesulfonic acids, produces inferior results as to shade, color strength and uniformity of dyeing.

TABLE 5 Appearance of 7 02. wool flannel dyed with 2% Chromacyl Bordeaux R A 'dU d D fiF of Dye Sh d 1 01 S8 ycing l 1010- a 6 scopic Exam.) Strengthl 8%HzSO4 Very Good. 4 I l 3% ASA-+295 H2804 do 1 2 3% Acet1c+2% HzSO4 2-3 3-4 8% ASA 2-2 2:2 5 5-6 7-8 78 7-8 78 9 9 10 10 11 11 1=strongest.

l=desired red shade. Other numbers refer to progressively bluer shades.

The dye baths and process of this present invention are applicable also to chemically modified wools, particularly wools which have been rendered shrink-resistant by treatment with active chlorine, as in the Harri'set process (note for example, Ind. Eng. Chem. 40, 2280-4 (December, 1948)). The chlorine-treated wool fabric has higher initial alkali solubility than untreated wool and is more easily damaged during dyeing, but can be satisfactorily dyed with less acid. I

In Table 6 are shown the results obtained in dyeing a Harriset shrink-resistant wool fabric as compared with an untreated fabric of identical. construction. The ASA of Table 6 refers to a mixture of C1C4 alkanesulfonic acids. It was found that only 1% of alkanesulfonic acid was required to give good dyeing of the Harriset-treated fabric, which amount of sulfonic acid causes approximately no increasein the alkali solubility of the wool. It was found that 4% of sulfuric acid was the necessary minimum to obtain satisfactory dyeing of the Harriset-treated fabric and it will'be noted that this amount of sulfuric acid doubled the alkali solubility of the wool fabic. It is most important to note that the same dye shade is produced by treatment of the Harriset-treated Wool with dye baths containing either the C1C4 alkanesulfonic acids or sulfuric acid. It is observed, therefore, that the use of C1C'4 alkanesulfonic acids presents marked advantages over sulfuric acid in dye baths 'for the treatment of Wool fabrics which have been rendered shrinkresistant byan active chlorinating agent such as sodium hypochlorite.

TABLE 6 Dyeing Harriset-treated? oz. grey wool flannel with Chromacyl "Bordeaux R The Harriset treatment is covered in U. S. Patent 2,466,695 .of Frishman and Harris, patented April 12,1949.

1 These samples were not dyed before making the measurements. In'dyeing Harriset shrink-resistant Wool yarn with dye baths containing mixtures of 0.25 or 1% of alkanesulfouic acids and 1% of H2804 the shades produced were about as good as those obtained with sulfuric acid alone, the exhausts were complete, the color strength was high and microscopic examination of the wool fibers indicated good levelness in dyeing.

Although I have provided illustrative examples of specific applications of my invention, it should be understood that my invention is not limited thereto. Thus, the acid dye baths and processes of my invention may be applied not only to virginor chemically modified wool, but to animal hair in general, since such hair is known to bevery similar, chemically, to woo1-and to be sensitive to sulfuric acid. For the present purpose it may be remarked that by acid-sensitivity I intend to denote substantial loss of strength or substantial increase in alkali solu--v bility following upon contact of the fiber in question with 8 weight percent of sulfuric acid at normal dyeing temperatures, usually at temperatures of about 150 F. or higher. The acid dye baths and dyeing process of the present invention may also be applied to synthetic, acid-sensitive protein fibers such as regenerated casein which has been treated with formaldehyde (Aralac, for example), soybean proteins, protein fibers derived from peanuts (Ardil, for example) and nylon-type fibers. The invention is also applicable to dyeing mixed fabrics containing wool or other acid-sensitive protein-type fiber,

' It will be appreciated that the baths and dye and water based'on the weight of the fabric-to be treated which are used in the, conventional procedures for applying aciddyes and between about 1 and about 10 weight percent of the alkanesulfonic acid, optionally together withxbetween about 0.5 and about 5 weight percent of sulfuric acid.

Having thus described my invention what I claim is:

1. A process for dyeing wool fiber, which process comprises contacting said fiber with an acid dye bath comprising essentially a metallized azo dye and between about 1 and about 10 percent by weight, based on said fiber, of an alkanesulfonic acid having l-to 4 carbon atoms, inclusive, in the molecule.

2. A process for dyeing wool fiber, whichprocess comprises contacting said fiber with an acid dye bath comprising essentially a. metalliz'ed azo dye and between about land about 10 percent by weight, based on said .fiber, of a mixture of alkanesulfonic acids having 1 to 4 carbon atoms, inclusive, in the molecule.

3. .A processior dyeing wool fiber, which process comprises contacting said fiber with .anacid dye bath comprisin essentially a chromiferous azo dye and. between about 1 and about .10 per.- cent by weight, based on said fiber, of an alkanesulfonic acid having 1 to 4 carbon atoms, inclusive, in the molecule.

4. A process for dyeing woolfiber, which process comprises contacting said fiber with an acid dye bath comprising essentially a chromiferous azo dye and between about 1 and about 10 percent by weight, based on said fiber, of a. mixture of alkanesulfonic acids having 1 to 4 carbon atoms, inclusive, in the molecule.

5. A dye bath comprising essentially a metallized azo dyestuif and an alkanesulfonic acid having 1 to 4 carbon atoms, inclusive, in the molecule.

6. A dye bath comprising essentially a chromiferous azo dyestuif and an alkanesulfonic acid having 1 to 4 carbon atoms, inclusive, in the molecule.

'7. A process for dyeing a shrink-resistant wool fiber which has been prepared by treatment with active chlorine, which process comprises contacting said fibers with an acid dye bath comprising essentially a chromiferous azo dye and an alkanesulfonic acid having 1 to 4 carbon atoms, inclusive, per molecule in an amount sufficient to induce substantialy dye fixation upon said fiber but not in excess of about 1 percent by weight based on said fiber, whereby dyeing of said fiber without substantial increase in the alkali solubility of said fiber results.

ANTHONY M. SCHWARTZ.

REFERENCES CITED The following references are of record in the file of'this patent:

UNITED STATES PATENTS Number Name Date 1,864,718 Feibelmann June'28, 1932 2,433,395 Proell Dec. 30,1947 2,433,396 Proell c..-....-Dec.30,1947

Certificate of Correction Patent N 0. 2,572,954 October 30, 1951 ANTHONY M. SCHWARTZ It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 33, for switch read swatch; columns 3 and 4, Table I, last column thereof, opposite Run 6, for :25 6 read 495.6; column 8, line 60, for substantialy read substantial;

THOMAS F. MURPHY,

Assistant Gammz'ssz'oner of Patents. 

1. A PROCESS FOR DYEING WOOL FIBER, WHICH PROCESS COMPRISES CONTACTING SAID FIBER WITH AN ACID DYE BATH COMPRISING ESSENTIALLY A METALLIZED AZO DYE AND BETWEEN ABOUT 1 AND ABOUT 10 PERCENT BY WEIGHT, BASED ON SAID FIBER, OF AN ALKANESULFONIC ACID HAVING 1 TO 10 CARBON ATOMS, INCLUSIVE, IN THE MOLECULE. 